Fiber Channel Storage Area Networks Explained

EMC Proven Professional. Copyright © 2012 EMC Corporation. All Rights Reserved.

MODULE – 5

FIBRE CHANNEL STORAGE AREA NETWORK (FC SAN)

Module 5: Fibre Channel Storage Area Network 1


Upon completion of this module, you should be able to:• Describe FC SAN and its components• Describe FC architecture• Describe FC SAN topologies and zoning• Describe virtualization in a SAN environment


Module 5: Fibre Channel Storage Area Network (FC SAN)



During this lesson the following topics are covered:• Evolution of FC SAN• Components of FC SAN• FC interconnectivity options• FC port types

Lesson 1: Overview of FC SAN



Business Needs and Technology Challenges

• An effective information management solution must provide: Just-in-time information to business users Flexible and resilient storage infrastructure

• Information management challenges in DAS environment: Explosive growth of information storage that remains isolated and

underutilized Proliferation of new servers and applications Complexity in sharing storage resources across multiple servers High cost of managing information

• Storage area network (SAN) addresses these challenges



What is a SAN?

• Centralizes storage and management• Enables sharing of storage resources across multiple servers at

block level• Meets increasing storage demands efficiently with better

economies of scale• Common SAN deployments are:

Fibre Channel (FC) SAN: uses FC protocol for communication IP SAN: uses IP-based protocols for communication


It is a high-speed, dedicated network of servers and shared storage devices.

SAN


Understanding Fibre Channel

• High-speed network technology Latest FC implementation supports speed up to 16 Gb/s

• Highly scalable Theoretically, accommodate approximately 15 million devices


Clients Storage ArraysApplication Servers

IPNetwork FC SAN


Components of FC SAN

• Node (server and storage) ports• Cables• Connectors• Interconnecting devices such as FC switches and hubs• SAN management software



Node Ports

• Provide physical interface for communicating with other nodes • Exist on

HBA in server Front-end adapters in storage

• Each port has a transmit (Tx) link and a receive (Rx) link


Link

Port 0Rx

Tx

Node

Port 0

Port 1

Port n


Cables

• SAN implementation uses Copper cables for short distance Optical fiber cables for long distance

• Two types of optical cables: single-mode and multimode


Single-mode

Multimode

Carries single beam of light

Can carry multiple beams of light simultaneously

Distance up to 10km

Used for short distance (Modal dispersion weakens signal strength after certain distance )

Light I n

Cladding Core

(b) Single-m ode Fiber

Light I n

Cladding Core

(a) Multi-m ode Fiber

Multimode Fiber

Light I n

Cladding Core

(b) Single-m ode Fiber

Light I n

Cladding Core

(a) Multi-m ode Fiber

Single-mode Fiber


Connectors

• Attached at the end of a cable• Enable swift connection and disconnection

of the cable to and from a port• Commonly used connectors for fiber optic

cables are: Standard Connector (SC)

Duplex connectors Lucent Connector (LC)

Duplex connectors Straight Tip (ST)

Patch panel connectors Simplex connectors


Straight Tip Connector

Lucent Connector

Standard Connector


Interconnecting Devices

• Commonly used interconnecting devices in FC SAN are: Hubs, switches, and directors

• Hubs provide limited connectivity and scalability• Switches and directors are intelligent devices

Switches are available with fixed port count or modular design Directors are always modular, and its port count can be increased

by inserting additional 'line cards' or 'blades' High-end switches and directors contain redundant components



SAN Management Software

• A suite of tools used in a SAN to manage interfaces between host and storage arrays• Provides integrated management of SAN

environment• Enables web-based management using GUI

or CLI



FC Interconnectivity Options

• Point-to-Point• Fibre Channel Arbitrated Loop (FC-AL)• Fibre Channel Switched Fabric (FC-SW)



Point-to-Point Connectivity

• Enables direct connection between nodes• Offers limited connectivity and scalability• Used in DAS environment


Servers

Storage Array

Server

Server


FC-AL Connectivity

• Provides shared loop to attached nodes Nodes must arbitrate to gain control

• Implemented using ring or star topology• Limitations of FC-AL

Only one device can perform I/O operation at a time

Supports up to 126 nodes Addition or removal of a node causes

momentary pause in loop traffic


Servers

Storage Array

Server

FC Hub


FC-SW Connectivity

• Creates a logical space (called fabric) in which all nodes communicate with one another using switches Interswitch links (ISLs) enable switches to be connected together

• Provides dedicated path between nodes• Addition/removal of node does not affect traffic of other nodes


Servers

Storage Array

Server

FC Switch FC Switch

Interswitch Links


Port Types in Switched Fabric


Server

N-Port

FC SwitchF-Port

FC Switch

Storage Array

N-Port

F-PortE-Port E-Port

Storage Array

N-Port

F-PortISL



During this lesson the following topics are covered:• FC protocol stack• FC addressing• WWN addressing• Structure and organization of FC data• Fabric services• Fabric login types

Lesson 2: Fibre Channel (FC) Architecture



FC Architecture Overview

• Provides benefits of both channel and network technologies Provides high performance with low protocol overheads Provides high scalability with long distance capability

• Implements SCSI over FC network Transports SCSI data through FC network

• Storage devices, attached to SAN, appear as local storage devices to host operating system



Fibre Channel Protocol Stack


FC Layer Function Features Specified by FC Layer

FC-4 Mapping interface Mapping upper layer protocol (e.g. SCSI) to lower FC layers

FC-3 Common services Not implemented

FC-2 Routing, flow control

Frame structure, FC addressing, flow control

FC-1 Encode/decode 8b/10b or 64b/66b encoding, bit and frame synchronization

FC-0 Physical layer Media, cables, connector

1 Gb/s 2 Gb/s 4 Gb/s 16 Gb/s

FC-4

FC-2

FC-1

FC-0

Upper Layer ProtocolExample: SCSI, HIPPI, ESCON, ATM, IP

Framing/Flow Control

Encode/Decode

8 Gb/s

Upper Layer Protocol Mapping


FC Addressing in Switched Fabric

• FC Address is assigned to nodes during fabric login Used for communication between nodes within FC SAN

• Address format

• Domain ID is a unique number provided to each switch in the fabric 239 addresses are available for domain ID

• Maximum possible number of node ports in a switched fabric: 239 domains X 256 areas X 256 ports = 15,663,104



World Wide Name (WWN)

• Unique 64 bit identifier• Static to node ports on an FC network

Similar to MAC address of NIC WWNN and WWPN are used to uniquely identify nodes and ports

respectively


World Wide Name - Array

50101

00000

00000

60110

00000

10001

60110

00000

00000

00000

60110

00000

00000

10001

B1011

20010

Company ID24 bits

Port Model Seed32 bits

World Wide Name - HBA

1 0 0 0 0 0 0 0 c 9 2 0 d c 4 0

Reserved12 bits

Company ID24 bits

Company Specific24 bits

FormatType

FormatType


Structure and Organization of FC Data

• FC data is organized as Exchange, Sequence, and Frame


FC Data Structure Description

Exchange

• Enables two N_Ports to identify and manage a set of information units• Information unit: upper layer protocol-specific

information that is sent to another port to perform certain operation

• Each information unit maps to a sequence• Includes one or more sequences

Sequence • Contiguous set of frames that correspond to an information unit

Frame• Fundamental unit of data transfer• Each frame consists of five parts: SOF, frame header, data

field, CRC, and EOF SOF4 Bytes

Data Field0 - 2112 Bytes

CRC4 Bytes

EOF4 Bytes

Frame Header24 Bytes

FC Frame


Fabric Services

• FC switches provide fabric services as defined in FC standards


Fabric Services Description

Fabric Login Server

• Used during the initial part of the node’s fabric login process• Located at pre-defined address of FFFFFE

Name Server • Responsible for name registration and management of node ports• Located at pre-defined address FFFFFC

Fabric Controller

• Responsible for managing and distributing Registered State Change Notifications (RSCNs) to attached node ports

• Responsible for distributing SW-RSCNs to every other switch− SW-RSCNs keep the name server up-to-date on all switches

• Located at pre-defined address FFFFFD

Management Server

• Enables FC SAN management using fabric management software• Located at pre-defined address FFFFFA


Login Types in Switched Fabric

• Fabric login (FLOGI) Occurs between an N_Port and an F_Port Node sends a FLOGI frame with WWN to Fabric Login Server on

switch Node obtains FC address from switch Immediately after FLOGI, N_Port registers with Name Server on

switch, indicating its WWN, port type, assigned FC address, etc. N_Port queries name server about all other logged in ports

• Port login (PLOGI) Occurs between two N_Ports to establish a session Exchange service parameters relevant to the session

• Process login (PRLI) Occurs between two N_Ports to exchange ULP related parameters




During this lesson the following topics are covered:• Mesh and core-edge topologies• Benefits of zoning• Types of zoning

Lesson 3: FC SAN Topologies and Zoning



Mesh Topology

• Full mesh Each switch is connected to every other

switch Maximum of one ISL or hop is required

for host-to-storage traffic Host and storage can be connected to

any switch

• Partial mesh Not all the switches are connected to

every other switch


FC Switches

Storage Array

Server

Full Mesh

FC Switches

Storage Array

Server

Partial Mesh


Core-edge Topology

• Consists of edge and core switch tiers• Network traffic traverses

core tier or terminate at core tier• Storage is usually

connected to the core tier• Benefits

High availability Medium scalability Medium to maximum

connectivity


FC Switch FC Switch FC Switch

Storage ArrayFC DirectorServer

Edge Tier

Core Tier

FC Switch FC Switch FC Switch

Storage ArrayFC DirectorServer FC Director

Core Tier

Edge Tier


Zoning

• Zone set comprises zones• Each zone comprises zone

members (HBA and array ports)• Benefits

Restricts RSCN traffic Provides access control


It is an FC switch function that enables node ports within the fabric to be logically segmented into groups, and communicate with each other within the group.

Zoning

Storage Array

Servers

Array port

HBA Port

FC SAN

Server

Zone 1

Zone 2


Types of Zoning


Zone 2

Zone 3

Port 1

Port 5

WWN 10:00:00:00:C9:20:DC:40

WWN 10:00:00:00:C9:20:DC:56

WWN 10:00:00:00:C9:20:DC:82

WWN 50:06:04:82:E8:91:2B:9E

Zone 1 (WWN Zone) = 10:00:00:00:C9:20:DC:82 ; 50:06:04:82:E8:91:2B:9EZone 2 (Port Zone) = 15,5 ; 15,12Zone 3 (Mixed Zone) = 10:00:00:00:C9:20:DC:56 ; 15,12

Servers

Storage ArrayFC Switch

Switch Domain ID = 15

Zone 1

Port 12Port 9


The potential for any server on a SAN to mount and access any drive on the SAN can create several problems. The two most prominent ones are disk resource contention and data corruption. To deal with these problems, you can isolate and protect storage devices on a SAN by using zoning and LUN masking, which allow you to dedicate storage devices on the SAN to individual servers.ZoningMany devices and nodes can be attached to a SAN. When data is stored in a single cloud, or storage entity, it is important to control which hosts have access to specific devices. Zoning controls access from one node to another. Zoning lets you isolate a single server to a group of storage devices or a single storage device, or associate a grouping of multiple servers with one or more storage devices, as might be needed in a server cluster deployment.Zoning is implemented at the hardware level (by using the capabilities of Fibre Channel switches) and can usually be done either on a port basis (hard zoning) or on a World-Wide Name (WWN) basis (soft zoning). WWNs are 64-bit identifiers for devices or ports. All devices with multiple ports have WWNs for each port, which provides more detailed management. Because of their length, WWNs are expressed in hexadecimal numbers, similarly to MAC addresses on network adapters. Zoning is configured on a per-target and initiator basis. Consequently, if you need to attach multiple nonclustered nodes to the same storage port, you must also use LUN masking.LUN maskingLUN masking, performed at the storage controller level, allows you to define relationships between LUNs and individual servers. Storage controllers usually provide the means for creating LUN-level access controls that allow access to a given LUN by one or more hosts. By providing this access control at the storage controller, the controller itself enforces access policies to the devices. LUN masking provides more detailed security than zoning, because LUNs provide a means for sharing storage at the port level.When properly implemented, LUN masking fully isolates servers and storage from events such as resets. This is critical for preventing the problems previously noted. It is important to thoroughly test your design and implementation of LUN masking, especially if you use LUN masking in server clusters.




During this lesson the following topics are covered:• Block-level storage virtualization• Virtual SAN

Lesson 4: Virtualization in SAN



Block-level Storage Virtualization

• Provides a virtualization layer in SAN• Abstracts block storage

devices and creates a storage pool by aggregating LUNs• Virtual volumes are

created from storage pool and assigned to hosts Virtualization layer maps

virtual volumes to LUNs • Benefits

Online volume expansion Nondisruptive migration


Virtual Volume

Storage Array Storage Array

Server

Virtualization Appliance

Servers

LUN

LUN

LUN

LUN

FC SAN

Storage Pool


Use Case: Block-level Storage Virtualization across Data Centers


Data Center 2Data Center 1Servers

Server Server

Storage Arrays Storage Arrays

Virtualization Layer

Virtualization Appliance

VirtualVolumes

Servers

FC or IP

VirtualVolumes

FC SAN FC SAN


Virtual SAN (VSAN)/Virtual Fabric

• Each VSAN has its own fabric services (name server, zoning), configuration, and set of FC addresses • VSANs improve SAN security,

scalability, availability, and manageability


It is a logical fabric on an FC SAN, enabling communication among a group of nodes, regardless of their physical location in the fabric.

VSAN

Storage Array Storage Array

Servers Servers

Server Server

FC SAN

VSAN 20VSAN 10



• EMC Connectrix• EMC VPLEX

Concept in Practice:



EMC Connectrix

• Connectrix family includes networked storage connectivity products Offers high-speed FC connectivity, highly resilient switching

technology, intelligent IP storage networking, and I/O consolidation with Fibre Channel over Ethernet

• Connectrix family consist of enterprise directors, departmental switches, and multi-purpose switches



EMC VPLEX

• Provides solution for block-level storage virtualization and data mobility – both within and across data centers• Enables multiple hosts located across two locations to access a

single copy of data• Provides capability to mirror a virtual volume – both within and

across locations Allows hosts at different data centers to simultaneously access

cache-coherent copies of the same virtual volume

• VPLEX family consists of three products VPLEX Local VPLEX Metro VPLEX Geo



Module 5: Summary

Key points covered in this module:• FC SAN components and connectivity options• FC protocol stack and addressing• Structure and organization of FC data• Fabric services• Fabric topologies • Types of zoning• Block-level storage virtualization and virtual SAN



Check Your Knowledge – 1

• Which cable type provides minimum signal attenuation over long distance?A. Twisted-pair copperB. Coaxial copperC. Single-mode optical D. Multimode optical

• What is an F_Port in FC SAN?A. Switch port that connects an E_PortB. Switch port that connects an N_PortC. Node port that connects an N_PortD. Node port that connects an E_Port




• Which type of fabric login enables the exchange of upper layer protocol-related parameters between N_Ports? A. Fabric loginB. Port loginC. Process login D. ULP login

• Which is a benefit of zoning in FC SAN?A. Isolates fabric services B. Restricts RSCN trafficC. Enables online volume expansionD. Provides non-disruptive data migration




• Which is a benefit of VSAN?A. Eliminates need for fabric login process B. Provides higher network bandwidthC. Improves security by isolating traffic between VSANsD. Enables VSANs to share fabric zoning service



Exercise: FC SAN

• Current situation An organization’s IT infrastructure consists of three storage arrays

direct-attached to a heterogeneous mix of 45 servers Servers are dual-attached to the arrays to ensure high availability Each storage array has 32 front-end ports, which could support

maximum of 16 servers Each storage array has the disk capacity to support a maximum of

32 servers



Exercise: FC SAN (contd..)

• Organization’s challenges/requirements Organization needs to deploy additional 45 servers to meet growth

requirements Existing storage arrays are poorly utilized and adding of new

servers require to purchase new arrays Organization wants to implement FC SAN to overcome the

scalability and utilization challenges Hop count must be minimized to meet performance requirement

• Task Propose a FC switched fabric topology to address organization’s

challenges/requirements and justify your choice If 72-port FC switches are available, determine the minimum

number of switches required in the fabric


Documents

Fiber Channel Storage Area Networks Explained